Intrapulmonary Teratoma.

Teratomata arise, in order of frequency, in the ovaries, testes, anterior mediastinum, retroperitoneal region, presacral and coccygeal regions, pineal and other intracranial sites, neck, and abdominal viscera other than the gonads (Willis, 1951). Mediastinal teratomata rank third among all teratoid tumours and are the second most common mediastinal tumours (Inada and Nakano, 1958). The majority of all intrathoracic teratomata are mediastinal, and those occurring in the lungs are among the rarest tumours encountered in pathology (Spencer, 1962). Before embarking on a review of the literature on intrapulmonary teratomata, it is desirable to establish an acceptable definition of what is meant by a 'teratoma'. Without such a definition, reports of cases designated as 'dermoid cysts' and 'hamartomata' might not lend themselves for classification into this group of tumours. Willis (1951) emphasized the neoplastic nature of the teratoma by defining it as a 'true tumour or neoplasm composed of multiple tissues foreign to the part in which it arises'. This definition excludes pulmonary hamartomata (Liebow, 1952) since no tissues foreign to the lung are present. Dermoid cysts, frequently recorded as synonymous with teratomata (Spencer, 1962), may be included in the group of teratoid tumours provided they contain other tissues besides skin (Willis, 1951). The following is a brief review of all the cases of intrapulmonary teratomata on record and a report of a new case exhibiting multiple clinicopathological findings.